This study presents a new microelectromechanical system, a vibration ring gyroscope with a double U-beam (DUVRG), which was designed using a combination of mathematical analysis and the finite element method. First, a ring vibration resonator with eight double U-beam structures was developed, and 24 capacitive electrodes were designed for drive and sense according to the advantageous characteristics of a thin-shell vibrating gyroscope. Then, based on the elastic mechanics and thin-shell theory, a mathematical stiffness model of the double U-beam was established. The maximum mode resonant frequency error calculated by the DUVRG stiffness model, finite element analysis (FEA) and experiments was 0.04%. DUVRG structures were manufactured by an efficient fabrication process using silicon-on-glass (SOG) and deep reactive ion etching (DRIE), and the FEA value and theoretical calculation had differences of 5.33% and 5.36% with the measured resonant frequency value, respectively. Finally, the static and dynamic performance of the fabricated DUVRG was tested, and the bias instability and angular random walk were less than 8.86 (°)/h and 0.776 (°)/√h, respectively.
This paper presents a sense mode closed-loop method for dual-mass micro-electro-mechanical system (MEMS) gyroscope based on the bipole temperature compensation method. A pair of conjugate poles are investigated as the bottle neck of the sense closed-loop system of MEMS gyroscope, and the bipole temperature compensation proportional controller (BTCPC) is employed to realize the closed-loop: a pair of additional conjugate zeros are utilized to generate bipoles with poles. Since poles changes with temperature, thermal resistance is utilized in BTCPC to make zeros variable with temperatures. The BTCPC is designed very carefully to make the system have enough bandwidth and better performance. The overall gyroscope model is established and simulated either in the time domain or the frequency domain, and the results verify that the sense closed-loop works rapidly and steadily. The system is realized on PCBs and is tested on the turntable in temperature oven. The experimental results show that the bias stability, angular random walking, bias temperature coefficient, and the bandwidth values of sense open-loop and closed-loop are 2.168 • /h, 0.155 • / √ h, 9.534 • /h/ • C, 13 Hz, and 2.168 • /h, 0.140 • / √ h (five tests average value), 5.991 • /h • C, 61 Hz, respectively. INDEX TERMS Dual-mass MEMS gyroscope, bipole-temperature compensation controller, experiment, sense closed-loop.
A closed-loop controlling system for Micro Electro Mechanical System (MEMS) gyroscope sense mode is investigated in this paper, and the controller is designed to achieve low error, wide bandwidth and low noise capability. The gyroscope monitoring system includes four independent closed-loop, and is simulated by Simulink soft to prove the speedability and stability of the sensing closed-loop. The gyroscope monitoring system is realized through 3 analog circuit boards, and is tested through temperature controlled turntable. The bias stability, angular random walking value and bias temperature coefficients improved from 2.168 • /h, 0.155 • / √ h and 10.59 • /h/ • C to 0.415 • /h, 0.0414 • / √ h and 3.59 • /h/ • C. And the bandwidth value is improved from 13Hz to 104Hz. Meanwhile, scale factor nonlinearity, asymmetry, repeatability and temperature coefficient parameters are enhanced from 660 ppm, 430ppm, 403ppm and 180 ppm/ • C to 59.3ppm, 62.4ppm, 50.4ppm and 28.7 ppm/ • C respectively. INDEX TERMS Micro Electro Mechanical System (MEMS) gyroscope, sensing closed-loop, experiment, quadrature error, step response.
In this paper, we propose a simple, low cost and mass producible nanoimprint lithography (NIL) method to texture the surface of GaN-based light emitting diodes (LEDs) with a two-dimensional photonic crystal (2DPC). Such a 2DPC structure not only enhanced the light output power but also changed the far-field pattern simultaneously. Also, a TiO 2 /SiO 2 omnidirectional reflector (ODR) was deposited on the backside of the LEDs to further increase the light output power. Under 350 mA current injection, it was found that forward voltages were 3.35, 3.34 and 3.75 V while the light output powers of the LEDs were 59.5, 92.5 and 112.1 mW for the conventional LED, the PCLED with 20 nm depth, and the PCLED with 120 nm depth all with chip size of 1 mm × 1 mm, respectively. A 88.4% enhancement in light output power of PCLED with a 120 nm depth and ODR on the backside could be achieved when compared to the conventional LED under the driving current of 350 mA. From the measurement results, it was also found that the NIL process does not degrade the electrical properties of the fabricated LEDs.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.